In a pneumatic tire that has a traction pattern, width direction grooves are arranged in a tread center area and tread shoulder areas to ensure the snow traction performance. However, the traction pattern easily deteriorates the low rolling resistance of the tire. The above configuration has an objective to improve the low rolling resistance while the snow traction performance of the tire is maintained.
As a conventional pneumatic tire with the above objective, the technology disclosed in Patent Document 1 is known. In the conventional pneumatic tire (heavy load radial tire), four longitudinal main grooves that continuously extend in a circumferential direction and have a groove width not less than 3.0 mm and not more than 19.0 mm and lateral grooves that intersect with the longitudinal grooves are provided on a tread surface, so that the tread surface is sectioned into a center block line consisting of blocks arranged in the circumferential direction on a tire equator; a pair of shoulder block lines consisting of blocks arranged in the circumferential direction along a tread edge; and a pair of middle block lines consisting of blocks arranged in the circumferential direction between the center block line and the shoulder block lines. The pneumatic tire has the following characteristics. The longitudinal main grooves include two or more longitudinal main grooves each having a groove width equal to or larger than 7.0 mm. A distance L from the center of the longitudinal main groove on an outer side in a tire axial direction to the tire equator is 0.25 to 0.35 of a width TW of a contact area by which the tread surface contacts with the ground in a normal state where the tire is mounted on a standard rim, filled with a standard internal force, and applied with a standard load. The lateral grooves that form the middle block lines are arc-shaped lateral grooves that have arc centers in the middle block lines and curve. A ratio S1/S of a total S1 of an area of the longitudinal main grooves and the lateral grooves to an area S of the contact area is 0.26 to 0.34. A lateral edge density E that is a ratio A/S of a total length A of lateral edge components of an edge portion formed by each edge of the longitudinal grooves and the lateral grooves, which are provided in the contact area, to the area S of the contact area is 0.025 to 0.035 (unit: mm/mm2). A lateral edge density ratio Es/Ec of a lateral edge density Ec of a center contact area of the contact area between the centers of the longitudinal main grooves on the outer side to a lateral edge density Es of outer contact areas of the contact area on outer sides of the center contact area is 0.60 to 0.85.
Patent Document 1: Japanese Patent Application Laid-open No. H11-245628